Modem automobiles are highly complex machines with many moving parts, some of which eventually wear out and require replacement. Some of the parts requiring replacement are attached to the vehicle with removable fasteners and therefore the parts can be removed by simply removing the removable fasteners. Other parts, especially suspension components, are attached to the vehicle or to other parts by a press fit. A press fit typically occurs where a part with an attachment portion of a given size is forced into an opening that is somewhat smaller in size than the attachment portion of the part. For example, a ball joint, which is a type of suspension bearing, has a cylindrical metal body which is pressed into a cylindrical bore in a suspension arm or spindle. The bore in the arm or spindle is somewhat smaller than the diameter of the cylindrical body of the ball joint, and therefore forcing the ball joint into the bore requires a great deal of force. The resulting assembly is simple but very strong.
A problem arises when an automotive mechanic needs to remove a part from an automobile which has been press fit into place. To disassemble press fit parts, the assembly procedure is reversed. One part is forced out of the other. Even under ideal conditions, disassembly of a press fit part requires a great deal of force. The problem is exacerbated where the press fit parts become corroded or dirt and debris become embedded around and between the parts. When an automobile is exposed to harsh conditions, corrosion can practically lock a press fit ball joint to a suspension spindle or arm.
Another problem with press fit parts is that many of these parts are complex in shape and are not readily adapted to be disassembled using a press or puller. To remove one press fit part from another the mechanic may use a hydraulic press or a puller of some type which exerts force on one press fit part relative to the other thereby forcing the two parts apart. Presses come in a variety of styles. One common style consists of a horizontal support surface with support members extending upward therefrom. The support members support some type of pressing member which can be moved vertically downward toward the support surface. The pressing member is typically moved by a hydraulic cylinder or other means capable of exerting a great deal of force. The pressing member can be used to exert force on items supported on the horizontal support surface. For example, if two parts which are pressed together are placed on the horizontal support surface, the pressing member can be used to exert force on one of the two parts. These types of presses typically are mounted on large stands or on the floor and are not portable. Another type of press resembles a heavy duty C-clamp. In this type of press, a pressing member is adjustably attached to a support member so that an item may be supported between the support member and the pressing member. Force can then be exerted by the pressing member on the supported item.
With any type of press, it is necessary that the parts which are to be pressed apart are shaped such that they can be supported in the press. Some parts do not meet this requirement as they are complex in shape, lacking a flat surface. This is particularly the case with ball joints which are press fit into suspension spindles. Suspension spindles can be complex in shape and lack flat surfaces for support in a press. A mechanic needing to remove a ball joint from a spindle typically must resort to clamping the spindle as best he can in a large, heavy duty vise and use a large sledge hammer to pound the ball joint out of the bore. This is time consuming, difficult, and potentially dangerous. Therefore, there is a need for a fixture for supporting a spindle so that the spindle may be placed in a press and the press used to press a ball joint out of the spindle.
There have been several attempts to provide tools to simplify the removal and installation of press fit parts. For example, the following patents disclose various exractors and pushers: U.S. Pat. No. 3,696,496 to Corder, U.S. Pat. No. 3,887,989 to Maynard and U.S. Pat. No. 5,404,631 to Boyd et al. The Corder invention includes a frame plate which is positioned on one side of a member containing a press fit part. A frame portion extends on the other side of the member and a drive means is supported by the frame portion and is used to exert force against the press fit part. The Corder invention is generally representative of self-contained pushers and pullers often used to assemble and disassemble press fit parts. These devices suffer from the shortcoming that the amount of force they can produce is limited by the drive means. Typically the drive means is some kind of threaded screw and therefore the amount of force is limited by the strength of the threads on the screw. The Corder invention, and other pushers and pullers similar to it, are not adapted to position a part or member below a press and therefore cannot benefit from the much greater force of which the press is capable of exerting. Conventional pushers and pullers also tend to be complex and potentially costly. Many serious automotive mechanics already own a heavy duty hydraulic press and therefore there is a need for a fixture which can support a spindle in the press thereby taking advantage of the ability of the press to exert a great deal of force.
Another approach is illustrated in U.S. Pat. No. 3,745,637 to Rutherford et al. The Rutherford invention is an adapter plate which allows the use of a conventional puller to remove ball joints from a spindle. Traditional pullers consist of two or more gripping arms and a pressing member, all of which extend from a main body. The gripping arms are used to grip an object having a press fit part therein. The pressing member is then brought to bear on the press fit part so that the jaws pull one direction on the object while the pressing member presses in the opposite direction on the press fit part. A disadvantage to traditional pullers is that many objects are not shaped to allow the gripping members to grip the object. The Rutherford invention helps overcome this limitation by providing an adapter plate which provides locations for gripping members to connect to an automotive part. However, the Rutherford invention is still limited in that it is designed to be used with a puller rather than with a press. Even the best of pullers are not capable of exerting the amount of force which even a small hydraulic press can create.